This invention relates to a method and an apparatus for removing fiber tufts from the surface of fiber bales such as cotton fiber bales, chemical fiber bales or the like. The apparatus has a tower which travels, by means of a carriage, along the fiber bales and on which there is mounted the opening device proper to remove the fiber tufts from the fiber bale surface. The opening device is movable vertically with respect to the tower; its vertical motion and the travelling motion of the tower are coordinated with one another by a control device. There is further provided a sensor device which detects foreign bodies, such as metal or wood fragments, foil particles, foreign fibers and the like contained in the fiber bales.
Risks are high that fiber bales contain foreign bodies, such as metal strap fragments, wire pieces, tools and the like. Such foreign bodies may cause damages in the textile machinery as early as the first processing step, that is, they may damage the bale opener in the course of the fiber bale opening process. Such foreign bodies may even cause a fire in the bale opener or the downstream-arranged fiber processing machines or such undesired foreign parts may gain access to subsequent fiber processing machinery.
Further, it is feasible that undesirable foreign fibers are contained in the cotton fiber bales and/or chemical fiber bales; such foreign fibers adversely affect the yarns, particularly the high-quality yarns. Such foreign fibers often remain in the cleaning and spinning installations in the useful fiber material during fiber processing and disadvantageously lead to discolorations. In many instances such impurities consist of jute, hemp or polypropylene fragments. The foreign fibers originate mostly from the packaging and from sacks which are used during harvesting. Foreign fibers, tying strings and the like are thus often present in the compressed fiber bales. The pressed-in tying strings often extend through several fiber layers (zones) in the fiber bale so that the bales often have to be dug into by hand to a substantial depth until the entire length of the foreign material can be removed. Such a foreign material removal is substantially labor-intensive and adversely affects the continuing work process.
In a known process for opening fiber bales, a sensor system recognizes foreign bodies (such as metal or wood fragments, sheet particles or foreign fibers), whereupon the fiber processing machine is immediately stopped and the foreign body is manually removed. The immediate stoppage of operation disadvantageously leads to a down time of the entire fiber processing line since substantial time is needed until maintenance personnel attend to the problem of removing the foreign body from the time the alarm signal or stoppage signal has been triggered. This procedure disadvantageously caused a significant reduction in output.